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Immunizations, Pathogens, Organ Systems

Human Herpes Virus- 6/7, Herpes Simplex virus,  PARVOVIRUS B19, HEPATITIS C, RSV

· Associated with exanthem subitum and CNS disease

· HHV-7 specific for acute hemiplegia of childhood

· HHV-8 (Kaposi's sarcoma herpes virus, KSHV)

· Cause of Kaposi's sarcoma

HHV-6: Epidemiology and Transmission

· Year-round, world wide distribution

· Antibody is present in 85% pregnant women, with active transport across placenta

· Newborn antibody levels decline in first 5 months of life (6%). The highest seroprevalence (86%) occurs at 1 year

· Lower mean titers are present after 40 years (60%)

· Increased prevalence IgM 6 months to 1 year of age

· Route of transmission: saliva most likely; no congenital or perinatal syndrome; not transmitted in breast milk

HHV-6: Clinical Manifestations

· Roseola (exanthem subitum, sixth disease)

· CNS: Febrile seizures, meningoencephalitis

· Nonspecific febrile illness

· Lymphadenopathy

· Hepatitis

· Intussusception

· Transplant patients: Pneumonitis, fever, mononucleosis-like

HHV-6: Association with CNS Disease

Exanthem subitum (ES) may be complicated by febrile (0.6-50%), bulging anterior fontanel, meningoencephalitis, hemiplegia, permanent paresis, mental retardation.

· Local production of antibody in CNS documented.

· HHV-6 gene sequence detected in brain tissue of child with ES and fatal fulminant hepatitis.

· Mechanism of association with febrile seizure: Reactivation of CNS HHV-6 by fever in patients with history of neurologic symptoms at time of acute ES.

· Possible etiologic role in multiple sclerosis HHV-6 virion syndrome proteins expressed in nuclei of oligodendrocytes in MS patients in association with MS plaques

HSV: Risk of Transmission to the Neonate

· First episode lesion: 50%

· First episode asymptomatic: 33%

· Recurrent lesion: 4%

· Known past infection, no visible

lesions/prodrome 0.04%

Other Risk Factors For Development of Neonatal Herpes

· Prematurity

· Prolonged rupture of membranes

· Vaginal delivery

· Scalp electrode

Prevention of Neonatal HSV: Minimal Obstetrical Role

· Vaccine not yet available

· Cultures during pregnancy

· Prenatal cultures are not predictive if neonatal infection

· Cultures are done at delivery in women with past history of herpes to facilitate early diagnosis of neonatal infection

· Recognition of active lesions during labor is usually followed by C-section delivery

· Antenatal acyclovir suppression is effective

Indications for Maternal Acyclovir

· Maternal varicella

· Severe first episode HSV

· Maternal immunosuppression associated with HSV recurrence

· Treatment or suppression of new herpes lesion formation in preterm premature ROM

Prevention of Neonatal HSV: Pediatric Role - Diagnosis and Therapy

· Skin lesions (40%)

· DFA of scraping of base: Sensitivity >80%, few false positives